The Role of p53 in Mouse Skin Keratinocytes

Stuart, Debra (1997) The Role of p53 in Mouse Skin Keratinocytes. PhD thesis, University of Glasgow.

Abstract

The aim of this project was to investigate the cellular events mediated by the tumour suppressor gene p53. Initially we chose to look in vitro at the response of p53 wild type and knockout keratinocyte cells to transforming growth factor beta (TGF?l) and ionising radiation, as p53 has been implicated in the cellular response to these agents. In vitro analysis showed that wild type p53 is not essential for mouse skin keratinocytes to execute a block in DNA synthesis in response to TGF?l. Furthermore, we found that the presence of wild type p53 does not alter the survival of mouse skin keratinocyte cells after exposure of up to l0Gy of ionising radiation. As the growing number of reports of p53 mediated cell type specific responses to ionising radiation became apparent, we decided to further our initial in vitro analysis of mouse skin keratinocytes and their response to ionising radiation by looking at specific keratinocyte populations in mouse epidermis after exposure to ionising radiation in vivo. We choose the relatively low dose of 4Gy for our in vivo experiments to avoid the complications of p53 independent cell death by necrosis at higher radiation doses. In epidermis, distinct populations of keratinocytes where identified which responded to p53 stabilisation by entering the apoptotic pathway or executing a cell cycle block. Cells within the matrix population of the hair follicle underwent p53 mediated apoptosis after exposure to radiation. The creation of p53 reporter mice allowed us to analyse the transcriptional activity of p53 induced by a number of agents in mouse epidermis. We found no evidence of p53 transcriptional activity in any population of keratinocytes in the skin after treatment with ionising radiation or tumour promoters. As an extension to the original study we looked at chemically induced tumour development in mouse skin pre treated with radiation which contained fewer matrix cells. The number of carcinogenic lesions which developed was significantly more than in normal mouse skin untreated with radiation. This was the case for both p53 wild type and knockout mouse skin. This led us to re-examine the role of mouse skin stem cells in tumour formation. Our results demonstrate that p53 induction and downstream events are regulated in not just a tissue specific manner but also a cell type specific manner within a tissue. These findings are of significant importance in the evaluation of sensitivity of individual cell types to DNA damaging agents, and are also relevant to the assessment of therapeutic treatment of tumours of varying origins.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Additional Information: Adviser: Bob Brown
• Keywords: Genetics
• Date of Award: 1997
• Depositing User: Enlighten Team
• Unique ID: glathesis:1997-75213
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 19 Nov 2019 21:45
• Last Modified: 19 Nov 2019 21:45
• URI: https://theses.gla.ac.uk/id/eprint/75213